Reconstruction

Multiple reconstructive techniques have been attempted in hopes of stabilizing the upper extremity after Tikhoff-Linberg procedure. A review of these methods is presented here with a discussion of their strengths and limitations.

Intramedullary Prosthesis

A Kuntscher nail is cemented into the medullary canal of the humerus, and subsequently fixed to the second rib or clavicular stump. Image from13

Strengths: Avoids excessive shortening of the humerus with better elbow power and stability for flexion13

Functional Spacer

A modular spacer is cemented distally into the humeral canal and sutured to the chest wall. Similar to the intramedullary rod, but its modular design allows for the length of the humerus to be patient-specific. Image from.19

Limitations: Little function of the shoulder is restored. The average overall function rating was 49% reported by O'Connor. 5/18 patients in this series had poor functional ratings for both positioning of the hand and lifting ability.

In one report, 7/18 patients had superior subluxation of the implant, and 5/18 had osteopenia and stress-shielding at the prosthesis-bone junction.19 Stem loosening was also a risk. See image at right.19

Custom-Made Humeral Prosthesis and Dual Suspension

Methyl methacrylate cement is injected into the humeral medullary canal and the prosthesis is placed with radial nerve anterior to it. Dual suspension refers to static and dynamic suspension. Static suspension: the prosthesis is fixed proximally to the clavicle alone or to the clavicle and remaining scapula with Dacron tape. Dynamic suspension: Muscle transfers are used to reinforce the joint and restore some function. Image from 3.

Strengths: Patients undergoing this procedure were not reported to have experienced shoulder pain or instability, and cosmetic results were considered acceptable. Functional range of motion was reported in all patients.

Limitations: Transient nerve palsies were the most common complication in the series reported by Malawer. The length of the remaining humerus may affect the potential for humeral prosthesis loosening. Other risks include insufficient soft tissue coverage and dislocation.20

Solid Scapular and Shoulder Joint Replacement

Prosthetic humeral and scapular components with an aortic Gortex graft sewn over the scapular neck and proximal humerus acting as a new joint capsule. The prosthesis are secured to the remaining rhomboids, latissimus dorsi, and teres major and minor. Image from 3.

Strengths: Early reports claimed 45 degrees of shoulder motion. Both the scapulothoracic and glenohumeral joints are active.

Limitations: The solid scapular prosthesis does not allow for scar ingrowth to secure the prosthesis. Also, significant soft-tissue salvage is required to cover the prosthesis. The Gortex graft is inherently elastic and does not replace normal rotator cuff stability.3

Frame Construction Scapular and Shoulder Joint Prosthesis

The frame construction decreases the weight of the endoprosthesis and allows scarring of the preserved serratus anterior and subscapularis to the more anterior retained portions of the infraspinatus, teres minor, and teres major.

Strengths: The Kaplan-Meier analysis (at right) of endoprosthetis survival at 5 and 8 years was 89% and 83%, respectively, in one recent report. The average MSTS functional rating was 74%. Only 1 of 14 patients experience a dislocation, the most common complication in this series. One patient experienced a deep wound infection 21. Image from21.

Limitations: Dislocation/subluxation, local recurrence with necessity to remove the endoprosthesis, loosening of the humeral stem, and deep infections are all potential concerns. Shoulder function and stability are still far from ideal.

Constrained Total Scapular Prosthesis

A modular humeral head and scapular prosthesis with glenoid snap together using a locking polyethylene liner, replacing the normal force vectors, i.e. stability, provided by the rotator cuff during active shoulder motion. Periscapular muscles spared from resection are tenodesed to the prosthesis and to each other.

Strengths: MSTS upper extremity functional score for 3 patients reported by Wittig, et al. was 80-90%. A stable, non-painful shoulder girdle was achieved. Hand and elbow function was retained. Though patients were not able to lift objects significantly above the shoulder level, internal rotation was nearly normal, and shoulder abduction and flexion were 20-25% of the normal side, compared with 5-20% in previous, non-constrained methods. Extension was equal to the normal side, and protraction, retraction, elevation, and depression were somewhat improved compared with previous methods. There were no complications in this small series, including no dislocations.22 Note how the constrained prosthesis restores normal force vectors, below. Image from 22.

MSTS upper extremity functional score reported more recently by Wodajo et al. was 86% with endoprosthetic reconstruction compared to 62% in patients with no endoprosthesis, including more active abduction (60-90% vs. 10-20%). Cosmesis was also improved.23

Limitations: High functional scores at the shoulder joint are dependent on the ability to preserve the deltoid and trapezius. Failure of the constrained liner have also been reported, resulting in dislocation.